Commutator



Jan. 5, 1932. v. G, APPLE ET AL COMMUTATOR Filed Sept. 21. 1.929

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Patented Jan. 5, 1932 Y,UNITI-:o STATES PATE NT OFFICE VINCENT G. APPLE .AND WALTER M'. DOEHRING, OF DAYTON, OHIO; SAID DOEHRING ASSIGNOR T SAID AIPLE COMMUTATOR Application led September 21, 1929. Serial No. 394,339.

This invention relates to commutators, and particularly to that class comprising a plurality of metal `segments of high electrical conductivity arranged in spaced apart cylindrical formation and held so positioned by a` core of insulating materia-l molded in situ about them.

To provide commutators of this class suitable for operation at high rotative speed, the material composing the core must possess considera-ble mechanical as well as dielectric strength, and inasmuch as a certain class of phenol-resin molding compounds meet this requirement they are most often used for the purpose.

But while commutator cores of phenolresin compounds serve particularly well as mechanical binders to hold the'segments in place and equally well asinsulation to extend etween the segments to hold them spaced apart, such insulation, extending between the segments, is not well adapted to extend outwardly therebetween to the brush track, since these materials do not make a goodV brush track because arcing of the brushes converts them to carbon which is a conductor.

To overcome this objection,` commutators of this class the segment spacers of insulating material are cut away at the brush track, the brushes beingr thick enough to ride over these cuts y without-ill effect, but preferably the insulation spacers which extend between the segments to hold them apartand insulate them one from another are composed of a different kind of. insulating material than the core, in which case the\two materials may each be of that nature most suitable for their re ective purposes.

It is t erefore an object of this invention to proceed in such a manner and with lsuch materials as will result in a commutator .wherein two kinds of insulation, each `suitable to its particular purpose are employed. We attain this object by the procedure and the resulting structure hereinafter described, reference being had to the drawings, where- 1n Fig. 1 is a perspective view of one of the 50 commutator segments.

are sometimes undercut,'i. e.,

to electrically `movement in channels Fig. 2 is a perspective view of one of the segment spacers.

Figs. 3 and 4 are perspective views of modified forms of segment spacers.

Fig. 5 is a vertical axial section through a mold containing a finished commutator.

Fig.. 6 is a transverse section taken at 6 6 of Fig. 5.

- Similar numerals refer to similar parts throughout the several views.

To carry out our method, commutator segments 10, Fig. 1, are first made by cutting wedge-shaped commutator bar stock into lengths and beveling the endsV as at 11. Next commutator segment spacers 12, Fig. 2, having enlarged inner edges 13 and having beveled ends as at 15 are molded of non-carbonsarily be shaped as at 13, Fig. 2, but may be modified as at 16, Fig. 3, as at 17, Fig. 4, or they may be any contour as long as the inner edge is thicker than the remainder of the spacer.

Having provided segments 10 and spacers 12 they are assembled in cylindrical formation in the mold 18, which comprises a body surrounded by a rotatable chuck ring 21 having a scroll 22 cut in its 'upper edge and bevel gear teeth 23 in its lower edge which are in turn adapted to mesh with teeth 25 of bevel pinion 26 on the end of the hand wrench 27. Four chuck jaws 28 have radial 30 in the top of body 2O and a circular cover plate 31 held to body 20 by screws 32 holds jaws 28 from upwardovement in the channels 30. The lower edges of the jaws 2 8 have scroll teeth 33 corresponding to the scroll 22. A stock ring concentrically supported on body 20 by annular rib 36 has the plunger 37 slidably fitted thereto. The bottom plug 38 has a pilot 40 of proper size to form the shaft bore of the commutator.

When the proper number of segments 10 are placed in the mold with spacers 12 between the segments, the wrench 27 is tightened so as to move jaws 28 radially inward, whereby the segments 10 are carried radially inward, thereby binding the spacers 12 tightly therebetween.

While the spacers are thus tightly bound between the segments, the mold is heated, the plunger 37 removed, a charge of unmolded insulation placed under the plunger and allowed to flux from the heat of the'mold then pressed about the segments and about the enlarged edges 13 of the spacers to form the core 41. When the heat remaining in the.

mold hassuliciently hardened the core, the jaws 28 are moved radially outward and the commutator is removed complete.

From the foregoing description it will be seen that a'commutator made by our improved method will have a core of a kind of molded insulation best suited to compose cores and segments spacers of another kind of insulation best suited to compose segment spacers, and that the spacers are held against radially outward movement by their enlarged inner edges.

Having described our claim- 1. A commutator comprising a plurality of separate segments of conductivematerial, an equal number of separate spacers of insulation between said segments, said spacers projecting inwardly beyond the inner edges of said segments, the spacers being thickened at the projecting inner edges, and a separate core of insulation within the cylindrical ring extending about the ends of the segments and spacers, the thickened inwardly projecting edges of the spacers being imbedded in and held by said core.

2. A commutator comprising a plurality of separate segments of conductive material arranged in the form of a cylinder, an equal number of separate spacers of insulation between said segments, said spacers having T- shaped inner edges projecting into the interior of said cylinder, and a core of insulation of a dii'erent kind from the insulation composing said spacers molded in situ into the interior of said cylinder, the T-shaped inner edges of said spacers being imbedded "T1 and held by said core.

In testimony whereof We affix our signatures.

VINCENT G. APPLE. WALTER M. DOEHRING.

invention, we 

